--------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2E00004 Date: 02/09/98 From: ARNOLD G. GILL Time: 04:18pm \/To: TIM EDWARDS (Read 2 times) Subj: Galaxy Missing Mass Hello TIM! On 07 Feb 98, TIM EDWARDS wrote to W BOSON: TE> Light does not always travel at it's limiting velocity, it is slowed TE> by fields that warp space. No, it is not. Light will always travel at the speed of light, when measured in any reference frame. "Warped space" increases the pathlength, so that it appears light has slowed down. In reality, it just has further to travel. TE> QED multiplies agents trying to explain observations that other TE> systems predict... it fails the Razor. QED also explains things that other theories do not, and makes predictions that are verified. Pretty good for a "failed" theory. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2E00005 Date: 02/09/98 From: ARNOLD G. GILL Time: 04:21pm \/To: BOB KING (Read 2 times) Subj: S. of L. Hello Bob! On 07 Feb 98, Bob King wrote to All: BK> Perhaps some of th experts in their field would like to comment on the BK> following article as, to me, it appears to contradict some of the BK> discussion going on here over the s. of l. I assume you mean the first article. BK> PHYSICS NEWS UPDATE The American BK> Institute of Physics Bulletin of Physics News Number 356 January 27, BK> 1998 by Phillip F. Schewe and Ben Stein BK> LOCALIZATION OF LIGHT has been achieved by an Amsterdam- Florence BK> collaboration (contact Ad Lagendijk, adlag@phys.uva.nl). Consider the BK> movement of light through a diffuse medium such as milk, fog, or BK> sugar. The light waves scatter repeatedly, and the transmission of BK> light decreases as the light gets reflected. In the Amsterdam-Florence BK> experiment something different happens. By using a gallium-arsenide BK> powder with a very high index of refraction but with very low BK> absorption at near infrared (wavelength of 1064 nm), the researchers BK> were, in a sense, able to get the light to stand still. That is, the BK> light waves get into the medium and bounce around in a standing wave BK> pattern, without being absorbed. This last sentence is the important one. They have produced a standing wave in such a way as to minimize absorption (i.e., the wave doesn't fade away). Sounds rather laser-like to me. Says nothing about the speed of light - a standing wave is just a wave that is reflected back and forth. You get the same thing when you see kids playing with a skipping rope. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2E00006 Date: 02/09/98 From: ARNOLD G. GILL Time: 04:24pm \/To: BOB KING (Read 2 times) Subj: S of L. Hello Bob! On 08 Feb 98, Bob King wrote to Arnold G. Gill: BK> If I am not mistaken though, I have often seen it mentioned that the BK> farther away an object is from us the greater the red shift, does this BK> not imply that the further away an object is the faster it is BK> receeding relative to us? Yes, but that does not mean it is accelerating. BK> Your objection on 'gravitational terms' BK> means to me that you consider the universe is therefore getting BK> smaller or at least staying a constant size,or expanding at a constant BK> rate,which is it? I understand that to date there has been no BK> confirmation that the universe has enough mass contained in it for BK> expansion to stop. Therefore is the expansion a constant? My objection is that gravity will naturally slow down the expansion over time. Gravity is a "pull" force, not a "push" force. The question that puzzles cosmologists is whether gravity is strong enough to _stop_ the expansion. It would be pretty for the answer to be yes (for example, demanding that the total energy of the universe be exactly zero --> the uncertainty principle - if applicible - then allows the universe to achieve an infinite age), but we don't know for sure yet. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2E00007 Date: 02/09/98 From: ARNOLD G. GILL Time: 04:30pm \/To: MIKE ROSS (Read 2 times) Subj: S of L. Hello MIKE! On 07 Feb 98, MIKE ROSS wrote to Arnold G. Gill: AGG>> Other than you, I have never heard anyone state that the rate of AGG>> expansion is increasing. I would be opposed to such a AGG>> statement, purely on gravitational terms. MR> This is exactly what I was reading into the meaning of that previous MR> report we discussed. The usual image is that expansion has a fixed MR> rate. If one says it is slowing down don't we mean the rate is MR> decreasing and if that's okay then why not the converse as well? Because gravity will slow the expansion - it cannot accelerate it. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2E00008 Date: 02/09/98 From: ARNOLD G. GILL Time: 04:32pm \/To: BOB KING (Read 2 times) Subj: S of L. Hello Bob! On 07 Feb 98, Bob King wrote to Sid Lee: SL>> happening in our universe since we are inherently 3 dimensional SL>> creatures BK> ??? 3-d I don't know about you but my universe is 4-d. Sid is talking about space dimensions here. You cannot "see" the time dimension, you experience it via a chain of experiences, but you have no control of your movement through it. Thus, time is fundamentally different from space. BK> I have a problem with imagining a 2d universe, to me the universe is BK> 4d. The reason I have a major problem with the analogy of the balloon BK> is because for a 4 dimensional object as we are,to envisage something BK> in only 2 dimensions is about as impossible as an intelligent 2 BK> dimensional object to envisage a 4 dimensional one. Not at all. You can see a point, a line, a square, a cube. You have just envisioned a 0D, 1D, 2D, and a 3D object. The analogy uses the fact that as a higher dimensional being, we can envision a 2D surface imbedded in a 3D universe. However, we cannot envision a 3D surface in a 4D universe, because we cannot comprehend the 4D universe. If you think Escher's art is offbeat, get someone to draw a 4D cube for you. It is the wierdest looking thing you have ever seen. Especially since you have to do a projection of the 4D cube onto a 2D surface, and then give it a partial rotation so that you can image the 3D surface. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2E00009 Date: 02/08/98 From: SID LEE Time: 08:21pm \/To: BOB KING (Read 2 times) Subj: S of L. -=> Quoting Bob King to Sid Lee <=- BK> saying but... I accept (I hope correctly) that the universe is BK> expanding at an ever increasing rate (so I am told) and although it As Arnold, and others have already repeatedly pointed out you appear to be the only one who seems to think the rate of expansion is increasing. As yet, to my knowledge at least ;-), you have not stated why this is. IN any event I think the state of the expansion trend is a "red herring". Relativity states quite clearly that regardless of the acceleration state of an object it can never, repeat never, reach the speed of light regardless of how hard it is "pushed". BK> doesn't agree with E=MC^2 because relative to us those bodies that are BK> far away from us do not get more massive relative to us, (perhaps you BK> could explain why under the hypothesis of relativity) I, for a start, BK> have a mental problem accepting 'massless' particles. I have even more BK> of a problem with accepting that if they are accelerated they gain BK> mass when they didn't have any in the first place. In other words you BK> have a piece of something which is nothing and increase its speed BK> relative to us and it promptly becomes more than nothing!! It isn't clear to me where these "massless" particles come from in your answer. Special relativity states that any object with a non-zero rest mass cannot be accelerated to the speed of light. A particle with a zero rest mass can only move at the speed of light. A "photon" is an example of such a body with zero rest mass. In point of fact if we could directly measure the apparent mass of a distant galaxy moving a substantial fraction of the speed of light (we cannot for purely technical difficulty reasons) we would strongly expect it to show an apparent mass well above its "rest mass". I get the feeling you are not correctly appreciating the meaning of the term "rest mass". The "rest mass" of an object is the mass measured for it by an observer for whom the object has no relative velocity. So, if we could measure the mass of a specific star in a galaxy moving rapidly with respect to us (because of the expansion of space or because the star had been accelerate by some other process) and an observer on a planet in orbit about that star (and hence moving effectively at its velocity) were to measure its mass the two measurements would disagree. We would measure it to be much more massive than he would. SImilarily if he and we measured the mass of our Sun we would get a much lower figure than he would. BK> You use the word 'apparently' gains mass, do they or BK> don't they? They do not gain mass in the sense of adding material to them. However when an object moves at any velocity with respect to the measurer all measurements assign it a mass greater than when the object is stationary with respect to the measurer. Hence the use of the term "apparently" ;-) > Special relativity is very well tested experimentally > and hardly a "premise" ;-) BK> I accept that it appears to be so when in close proximity to our own BK> frame of ref. but as above it does not appear to hold with very BK> distant objects. If it did then in the last 50 years or so we should BK> have been able to measure an increase in mass of some of the stars and BK> galaxies that are fairly distant from us. Well first of all 50 years is an incredibly short period of time when we look at faraway objects. We would not expect to be able a change in apparent mass of a distant galaxy simply because its change of position and hence of speed and hence of mass would be so tiny since we began taking spectra that we would not be able to come close to discern it. Consider this hypothetical scenario: Assume we have seen a galaxy much like our own (diameter 100,000 light years) which is far enough away from us to be receding at a velocity of 75% C. Further assume (ridiculous I know!) that we have comparitive measurements of its velocity now and 1000 years ago. In 1000 years moving at the assumed speed it would move 750 ly or 0.75% of its diameter. Not a big move! Now assume the Hubble constant (which characterizes the increase in apparent velocity with increasing distance) is a very high (by current thinking) 100 km/sec/megaparsec. A megaparsec is 1 million parsecs or roughly 3.25 million ly. Our galaxy has moved 750 ly further away since we first measured its velocity so it has gained: 750 x 100/3.25 x 10^6 = 0.023 km/sec of velocity between the 2 measurements from space expansion. In other words its velocity at the first measurement would have been 0.75C or about 225,000 km/sec and today it would be 225,000.023 km/sec, a change of about 1 part in 10^7, much too tiny to hope to detect. Of course our observations have actually been made over a much shorter time period (perhaps 50 years) so the real situation is much worse than this grossly exaggerated scenario shows. BK> there appears to be something wrong. Both theories relating to BK> relativity appear to work in a lot of cases but as I have pointed out BK> above they do not appear to work when logic is applied to them. In fact they have to date worked perfectly in all situations tested. BK> Massless particles (IMO) have about the same validity as the BB BK> starting from nothing.I cannot think of any example that we know of BK> where 'nothing' is in existance. If I had a piece of it I could throw That's true , you (or I for that matter ;-) cannot think of a single instance of somethng coming from nothing. However that rather reflects the characteristics of the space-time continuum we inhabit. It is in no way a reason to hold that such an event doesn't happen "routinely". By definition a BB could occur inyour teacup and because it would form its own universe as it did so, separate, distinct, and completely uncoupled from ours and unobservable from ours you wouldn't experience anything. -- Regards -- Sid Lee (FIDO - 1:134/122, Internet - sidlee@agt.net) --- Blue Wave/Max v2.12 * Origin: RASCAL BBS [Calgary, Alberta - (403)686-2550] (1:134/122) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2E00010 Date: 02/08/98 From: SID LEE Time: 08:22pm \/To: BOB KING (Read 2 times) Subj: S of L. -=> Quoting Bob King to Sid Lee <=- BK> Surface? How can an object such as our universe have a surface when BK> it has no edge/end that we know of? The only concept I get from this Contemplate the "balloon universe" ;-) -- Regards -- Sid Lee (FIDO - 1:134/122, Internet - sidlee@agt.net) --- Blue Wave/Max v2.12 * Origin: RASCAL BBS [Calgary, Alberta - (403)686-2550] (1:134/122) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2F00000 Date: 02/06/98 From: JAMES ROOT Time: 02:45pm \/To: KEITH KNAPP (Read 3 times) Subj: Re: 3D moon pix -=> Quoting Keith Knapp to All <=- KK> Okay, I gotta question for anyone who knows trig. KK> Back in the 19th century, one of the first people to photograph KK> the sun discovered a neat trick: Take one photo, then wait KK> 26 minutes and take an identical photo. During the interval, KK> the sun rotates just enough to simulate the parallax effect KK> of stereo vision. So if you put the two photos side by side KK> in a stereo viewer, you get a 3D image. KK> I've been trying to figure out how to apply this to the moon, KK> and I've rediscovered that my math skills stopped evolving KK> in the 8th grade. KK> Near as I can tell, in 26 minutes the sun rotates _approximately_ KK> 1/4 degree. KK> Assuming this is valid, what distance would you travel on the KK> earth to have your view of the moon change by 1/4 degree? KK> I'm sure anyone who knows the math and the rotation period KK> of the sun (it's about 3 1/2 weeks) could tap this out on a KK> calculator in two minutes, but I'm stumped! KK> Also, would the degree (therefore the distance) be different KK> for different magnifications? I.e., would you need a different KK> parallax for a whole-moon shot versus something at 400x? KK> Thx in advance! KK> * SLMR 2.1a * Smiley captioned for the irony impaired. KK> -!- PCBoard (R) v15.4/M 5 Beta KK> ! Origin: * Binary illusions BBS * Albuquerque, NM * KK> 505.897.8282 * (1:301/45) The angle subtended by an equatorial radius of the earth at the distance of the sun is known as solar parallax, and the angle subtended by the radius of the earth at the distance of any other member of the solar system is known as the horizontal parallax of that object. The average distance between the moon and the earth is 218,857 miles. The equatorial radius of the earth is 3963.53 miles. * moon | | 218,857 miles | | -----* earth (radius at equator = 3963.53 miles cot A = b / a = 218857/3963.53 = 55.217697 A = 1 degree, 2 minutes, or moon's parallax = 1 deg, 2 min 1 geographical degree = 68 miles (close enough), so you would have to drive, or have someone else photograph their view of the moon 70 miles away, at that same instant in time and at the same magnification. Using a different magnitude would effect the distance value of the moon's apparent distance as seen in your zoom shot. At least these are my reasonings, and as there must be a better way of doing this, he who knows please let me know! :-) James Due to the motions of the moon the same view always remains exposed to the earth, and it appears to not rotate at all. ... A clean desk is a sign of a cluttered desk drawer. ___ Blue Wave/QWK v2.12 --- Maximus 3.01 * Origin: Fun and Private Bbs (1:250/123) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2F00001 Date: 02/10/98 From: MIKE ROSS Time: 12:50pm \/To: ARNOLD G. GILL (Read 3 times) Subj: Re: S of L. Arnold G. Gill said the following to MIKE ROSS on the subject of S of L. (09 Feb 98 16:30:00) MR> report we discussed. The usual image is that expansion has a fixed MR> rate. If one says it is slowing down don't we mean the rate is MR> decreasing and if that's okay then why not the converse as well? AGG> Because gravity will slow the expansion - it cannot accelerate AGG> it. I fully understand but I don't think you should say "cannot". It is believed that there is no center of the universe and that each point is the center. Then why can't some force in the universe be tugging space apart at each point such that the expansion is accelerating? I can think of a way. For example, a surfer has to pick up momentum from paddling down a number of passing waves before he can finally catch up with the big one. The analogy here being that matter could still be accelerating from the gravitational shock wave energy released at the Big Bang. Each passing energy crest could be imparting momentum to matter a little bit at a time. We can see a similar kind of mechanism at work as the density waves which formed the arms of spiral galaxies. The one thing for certain is we aren't able to measure this wave energy because we don't know how to detect it and our life spans may be too short to observe it. On a similar distant tack, we are as impervious in such a case as when mysteriously epidemics killed millions before the electron microscope was invented and allowed us to see the cause was a virus agent. --- Blue Wave/DOS v2.30 * Origin: Juxtaposition BBS. Lasalle, Quebec, Canada (1:167/133) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2F00002 Date: 02/10/98 From: MIKE ROSS Time: 10:51am \/To: ARNOLD G. GILL (Read 3 times) Subj: Re: S of L. Arnold G. Gill said the following to Bob King on the subject of S of L. (09 Feb 98 16:32:06) AGG> On 07 Feb 98, Bob King wrote to Sid Lee: SL>> happening in our universe since we are inherently 3 dimensional SL>> creatures BK> ??? 3-d I don't know about you but my universe is 4-d. AGG> Sid is talking about space dimensions here. You cannot "see" the AGG> time dimension, you experience it via a chain of experiences, but you AGG> have no control of your movement through it. Thus, time is AGG> fundamentally different from space. BK> I have a problem with imagining a 2d universe, to me the universe is BK> 4d. The reason I have a major problem with the analogy of the balloon BK> is because for a 4 dimensional object as we are,to envisage something BK> in only 2 dimensions is about as impossible as an intelligent 2 BK> dimensional object to envisage a 4 dimensional one. AGG> Not at all. You can see a point, a line, a square, a cube. You AGG> have just envisioned a 0D, 1D, 2D, and a 3D object. The analogy uses AGG> the fact that as a higher dimensional being, we can envision a 2D AGG> surface imbedded in a 3D universe. However, we cannot envision a 3D AGG> surface in a 4D universe, because we cannot comprehend the 4D AGG> universe. AGG> If you think Escher's art is offbeat, get someone to draw a 4D AGG> cube for you. It is the wierdest looking thing you have ever seen. AGG> Especially since you have to do a projection of the 4D cube onto a 2D AGG> surface, and then give it a partial rotation so that you can image the AGG> 3D surface. AGG> Arnold G. Gill - astrophysician at play The curvature of space is yet another dimension which we can't perceive. There are also those dimensions which can only be experienced but by fundamental particles. --- Blue Wave/DOS v2.30 * Origin: Juxtaposition BBS. Lasalle, Quebec, Canada (1:167/133)